An integrative framework for addressing taxonomic challenges in Cystoseira s.l.

Brown algae within the Cystoseira sensu lato (s.l.) complex constitute essential components of Mediterranean marine forests, yet their taxonomic delineation remains a significant challenge due to pronounced phenotypic plasticity and recent reclassification into three distinct genera. These taxonomic uncertainties, further exacerbated by the addition of new species, impede conservation efforts and ecological research. To address these challenges, we developed an integrative framework combining advanced molecular tools with morphological assessments to achieve precise species identification and robust phylogenetic resolution. This standardized approach incorporates rapid DNA extraction techniques, high-resolution molecular markers (COI, RuBisCO, ITS2), and rigorous phylogenetic analyses, ensuring reliable results at both interspecific and intraspecific levels. Our comprehensive database, derived from Atlantic and Mediterranean specimens, provides critical insights into the taxonomy of Cystoseira s.s., resolving long-standing ambiguities. This framework not only enhances species classification accuracy but also supports future research, conservation planning, and ecosystem management strategies for Mediterranean marine forests.